SAN DIEGO — Rates of testicular cancer among young men have risen significantly over the last two decades across racial and ethnic groups, according to a new study, and researchers are wondering what accounts for it.

The study, scheduled for presentation Sunday at the 108th annual scientific meeting of the American Urological Association in San Diego, found that testicular cancer - the most common cancer among males between 15 and 34 - still had the highest incidence among Caucasians, but had risen 5.6% among Hispanics between 2002 and 2009, meaning Hispanics had the second highest rates, while African-Americans had the lowest.

Between 1992 and 2009, the rate among Caucasians rose from 7.5-per-100,000 people to 8.6-per-100,000, while the rate among Hispanics rose from 4-per-100,000 to 6.3-per-100,000, and the rate among African-Americans rose from 0.7-per-100,000 to 1.7-per-100,000.

"More research is needed to shed light on why the incidence is up nationwide and if any environmental factors or co-morbidities impact disease formation," University of Kansas Medical Center urology professor and director of urologic oncology Jeff Holzbeierlein said. "These new data confirm Hispanic-Americans should speak with their doctor about risk factors and be even more vigilant with their testicular health."